Thermo‑Mechanical Controlled Processing (TMCP)
Modern hot rolling is not just about thickness reduction; it is a precise thermal cycle that determines the final grain size, phase constituents, and thus the mechanical properties. CNB’s partner mills use advanced TMCP to achieve high strength without sacrificing weldability.

TMCP Parameters & Effects

• Roughing Temperature: Above recrystallization stop temperature (Tnr) to break down the cast structure.

• Finish Rolling Temperature: Just above Ar3 (austenite to ferrite transformation start) to produce a fine, deformed austenite grain that transforms into very fine ferrite upon cooling.

• Cooling Rate: Laminar cooling on the run‑out table controls the transformation rate. Faster cooling produces finer grains and can introduce bainite/acicular ferrite for higher strength.

• Grain Size: ASTM grain size 9‑12 is typical for thin‑gauge structural HR. Finer grain size simultaneously increases both yield strength and toughness (lower ductile‑to‑brittle transition temperature).

Typical Results (S355M/ Q355B)

• Yield Strength: 370‑450 MPa

• Tensile Strength: 510‑610 MPa

• Elongation: 22‑28%

• Impact Toughness: ≥27J at ‑20°C